The leading shock in a steady shock train takes one of two forms: oblique or normal. However, the phenomenon and mechanism of the normal-to-oblique transition of the leading shock in a forced shock train have not been widely reported. In this study, leading normal and oblique shocks are experimentally observed at the same position and similar velocities in a forced oscillation shock train with an incoming Mach number of 1.83. The normal-to-oblique transition is found to be closely related to the self-excited oscillation of the shock train. In addition, we find that the direct use of free-interaction theory cannot accurately predict the leading shock angle in a moving shock train. Thus, free-interaction theory requires appropriate correction for this scenario.

1.
K.
Matsuo
,
Y.
Miyazato
, and
H.
Kim
, “
Shock train and pseudo-shock phenomena in internal gas flows
,”
Prog. Aerosp. Sci
35
,
33
100
(
1999
).
2.
H.
Zare-Behtash
,
K. H.
Lo
,
K.
Kontis
,
T.
Ukai
, and
S.
Obayashi
, “
Transverse jet-cavity interactions with the influence of an impinging shock
,”
Int. J. Heat Fluid Flow
53
,
146
(
2015
).
3.
T.
Ukai
,
H.
Zare-Behtash
,
K. H.
Lo
,
K.
Kontis
, and
S.
Obayashi
, “
Effects of dual jets distance on mixing characteristics and flow path within a cavity in supersonic crossflow
,”
Int. J. Heat Fluid Flow
50
,
254
(
2014
).
4.
T.
Ukai
,
H.
Zare-Behtash
,
E.
Erdem
,
K. H.
Lo
,
K.
Kontis
, and
S.
Obayashi
, “
Effectiveness of jet location on mixing characteristics inside a cavity in supersonic flow
,”
Exp. Therm. Fluid Sci.
52
,
59
67
(
2014
).
5.
F.
Gnani
,
B. H.
Zare
, and
K.
Kontis
, “
Pseudo-shock waves and their interactions in high-speed intakes
,”
Prog. Aerosp. Sci.
82
,
36
56
(
2016
).
6.
A. C.
Idris
,
M. R.
Saad
,
B. H.
Zare
, and
K.
Kontis
, “
Luminescent measurement systems for the investigation of a scramjet inlet-isolator
,”
Sensors
14
,
6606
(
2014
).
7.
F.
Gnani
,
H.
Zare-Behtash
,
C.
White
, and
K.
Kontis
, “
Numerical investigation on three-dimensional shock train structures in rectangular isolators
,”
Eur. J. Mech. -B/Fluids
72
,
586
593
(
2018
).
8.
Y.
Miyazato
,
K.
Matsuo
, and
R.
Kasada
, “
Experimental and theoretical investigations of normal shock wave/turbulent boundary-layer interactions at low Mach numbers in a square straight duct,” in
Proceedings of 47th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition
(
American Institute of Aeronautics and Astronautics
,
Orlando, Florida
,
2009
), p.
925
.
9.
R. L.
Klomparens
,
J. F.
Driscoll
, and
M.
Gamba
, “
Boundary layer separation in a 3D shock train
,” AIAA Paper No. AIAA 2015-1519,
2009
.
10.
R. L.
Hunt
and
M.
Gamba
, “
Shock train unsteadiness characteristics, oblique-to-normal transition, and three-dimensional leading shock structure
,”
AIAA J.
56
,
1569
(
2018
).
11.
V. R. P.
Sethuraman
,
Y.
Yang
, and
J. G.
Kim
, “
Low-frequency shock train oscillation control in a constant area duct
,”
Phys. Fluids
34
,
016105
(
2022
).
12.
N.
Li
, “
Reciprocating and flapping motions of unstart shock in a scramjet isolator
,”
Phys. Fluids
34
(
1
),
016102
(
2022
).
13.
Z. A.
Wang
,
J. T.
Chang
,
G. W.
Wu
, and
D. R.
Yu
, “
Experimental investigation of shock train behavior in a supersonic isolator
,”
Phys. Fluids
33
,
046103
(
2021
).
14.
Z. A.
Wang
,
J. T.
Chang
,
Y. M.
Li
et al, “
Oscillation of the shock train under synchronous variation of incoming Mach number and backpressure
,”
Phys. Fluids
34
,
046104
(
2022
).
15.
Z. A.
Wang
,
J. T.
Chang
,
W. X.
Hou
, and
D. R.
Yu
, “
Low-frequency unsteadiness of shock-wave/boundary-layer interaction in an isolator with background waves
,”
Phys. Fluids
32
,
056105
(
2020
).
16.
T.
Ikui
,
K.
Matsuo
,
M.
Nagai
, and
M.
Honjo
, “
Oscillation phenomena of pseudo-shock waves
,”
Bull. JSME
17
,
1278
(
1974
).
17.
R.
Yamane
,
E.
Kondo
,
Y.
Tomita
, and
N.
Sakae
, “
Vibration of pseudo-shock in straight duct: 1st report, fluctuation of static pressure
,”
Bull. JSME
27
,
1385
(
1984
).
18.
R.
Yamane
,
M.
Takahashi
, and
H.
Saito
, “
Vibration of pseudo-shock in straight duct: 2nd report, calculation of static pressure fluctuation
,”
Bull. JSME
27
,
1393
(
1984
).
19.
H.
Sugiyama
,
H.
Takeda
,
J.
Zhang
,
K.
Okuda
, and
H.
Yamagishi
, “
Locations and oscillation phenomena of pseudo-shock waves in a straight rectangular duct
,”
JSME Int. J. Ser. 2, Fluids Eng. Heat Transfer, Power, Combust., Thermophys. Prop.
31
,
9
15
(
1988
).
20.
R. L.
Hunt
and
M.
Gamba
, “
On the origin and propagation of perturbations that cause shock train inherent unsteadiness
,”
J. Fluid Mech.
861
,
815
(
2019
).
21.
K.-C.
Lin
,
K.
Jackson
,
R.
Behdadnia
,
T. A.
Jackson
,
M.
Jackson
,
F. H.
Ma
, and
V.
Yang
, “
Acoustic characterization of an ethylene-fueled scramjet combustor with a rectangular cavity flameholder
,”
J. Propul. Power
26
,
5382
(
2007
).
22.
S.
Laurence
,
S.
Karl
,
J.
Schramm
, and
K.
Hannemann
, “
Transient fluid-combustion phenomena in a model scramjet
,”
J. Fluid Mech.
722
,
85
120
(
2013
).
23.
Y.
Tian
,
Y.
Han
,
S.
Yang
,
F.
Zhong
, and
J.
Le
, “
Investigation of fluctuating characteristics of wall shear stress in supersonic flow
,”
Phys. Fluids
31
,
125110
(
2019
).
24.
Y.
Tian
,
W.
Shi
,
F.
Zhong
, and
J.
Le
, “
Pilot hydrogen enhanced combustion in an ethylene-fueled scramjet combustor at Mach 4
,”
Phys. Fluids.
33
,
015105
(
2021
).
25.
F.
Gnani
,
H.
Zare-Behtash
,
C.
White
, and
K.
Kontis
, “
Effect of back-pressure forcing on shock train structures in rectangular channels
,”
Acta Astronaut.
145
,
471
481
(
2018
).
26.
B.
Xiong
,
X. Q.
Fan
,
Z. G.
Wang
, and
Y.
Tao
, “
Analysis and modelling of unsteady shock train motions
,”
J. Fluid Mech.
846
,
240
(
2018
).
27.
R.
Saravanan
,
S. L. N.
Desikan
, and
T. M.
Muruganandam
, “
Isolator characteristics under steady and oscillatory back pressures
,”
Phys. Fluids
32
,
096104
(
2020
).
28.
L. M.
Edelman
,
M.
Gamba
,
R.
Hunt
,
A.
Auslender
,
J. M.
Donbar
, and
M.
Hagenmaier
, “
Application of flux-conserved modeling to an unsteady combustion driven pseudo-shock
,” AIAA Paper No. AIAA 2021-1763,
2021
.
29.
B.
Xiong
,
X.-Q.
Fan
,
Y.
Wang
, and
Y.
Tao
, “
Experimental study on self-excited and forced oscillations of an oblique shock train
,”
J. Spacecr. Rockets
55
,
640
647
(
2018
).
30.
C.
Cheng
,
C.
Wang
, and
K.
Cheng
, “
Response of an oblique shock train to downstream periodic pressure perturbations
,”
Proc. Inst. Mech. Eng., Part G
233
,
57
70
(
2019
).
31.
B.
Xiong
,
Z. G.
Wang
,
X. Q.
Fan
, and
Y.
Wang
, “
Response of shock train to high-frequency fluctuating backpressure in an isolator
,”
J. Propul. Power
33
,
1520
(
2017
).
32.
H.
Babinsky
and
J. K.
Harvey
,
Shock Wave-Boundary-Layer Interactions
(
Cambridge University Press
,
2011
), pp.
41
53
.
33.
W.-Z.
Xie
,
S.-Z.
Yang
,
C.
Zeng
,
K.
Liao
,
R.-H.
Ding
,
L.
Zhang
, and
S.
Guo
, “
Improvement of the free-interaction theory for shock wave/turbulent boundary layer interactions
,”
Phys. Fluids
33
,
075104
(
2021
).
34.
H.
Chen
,
Q.-Z.
Zhang
,
W.-H.
Luo
, and
L.-J.
Yue
, “
Switching between symmetric and asymmetric separation-induced shock reflections in an oscillatory duct flow
,”
Phys. Fluids
34
,
071703
(
2022
).
35.
F. M.
White
,
Viscous Fluid Flow
,
2nd ed
. (
McGraw-Hill
,
New York
,
1991
), pp.
158
159
.
36.
A.
Kendall
and
M.
Koochesfahani
, “
A method for estimating wall friction in turbulent wall-bounded flows
,”
Exp. Fluids
44
,
773
780
(
2008
).
37.
D. R.
Chapman
,
D. M.
Kuehn
, and
H. K.
Larson
, “
Investigation of separated flows in supersonic and subsonic streams with emphasis on the effect of transition
,”
Report No. NACA-TR-1356
(National Advisory Council for Aeronautics,
1956
).
38.
J.
Erdos
and
A.
Pallone
, “
Shock-boundary layer interaction and flow separation
,” in
Proceedings of the Heat Transfer and Fluid Mechanics Institute
,
1962
.
39.
P. J. K.
Bruce
and
H.
Babinsky
, “
Unsteady shock wave dynamics
,”
J. Fluid Mech.
603
,
463
(
2008
).
40.
N.
Li
,
J.-T.
Chang
,
K.-J.
Xu
,
D.-R.
Yu
,
W.
Bao
, and
Y.-P.
Song
, “
Prediction dynamic model of shock train with complex background waves
,”
Phys. Fluids
29
,
116103
(
2017
).
41.
P. S. R.
Touré
and
E.
Schülein
, “
Scaling for steady and traveling shock wave/turbulent boundary layer interactions
,”
Exp. Fluids
61
,
156
(
2020
).
You do not currently have access to this content.